A roller carrier is a device which drives the cylindrical (or conical) weldment to rotate by the friction force between the weldment and driving rollers. The roller carrier can be categorized into self-aligning type, adjustable type, flatcar type, inclinable type, anti-axial shifting type and etc., among which the adjustable roller carrier comprises a roller carrier base, driving roller components and driven roller components. Currently, the adjustable roller carrier has three types, including manual lead-screw adjustable type, manual bolt displacement type and electric sliding plate displacement type, which all of these are satisfied weldment with different diameters by adjusted the center-to-center distance of rollers manually. Since all the existing adjustable roller carriers have defects of being large in structure and high in center height, manual or electric sliding plate adjustment structure causes the steel pipe to lift slowly; and the upper surface of the roller carrier base is horizontal, so weldment with large diameter is not stable and easy to roll when placed on the roller carrier. Though, under special environment, such as inside a tunnel, the operation position and space are restricted strictly, the current roller carriers cannot meet the operation requirements, which limits the application of the roller carriers.